Large thermoelectric power variations in epitaxial thin films of layered perovskite GdBaCo2O5.5±δwith a different preferred orientation and strain

This work describes the growth of thin epitaxial films of the layered perovskite material GdBaCoO(GBCO) on different single crystal substrates SrTiO(STO), (LaAlO)(SrTaAlO)(LSAT) and LaAlO(LAO) as an approach to study changes in the thermoelectric properties by means of the induced epitaxial strain....

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Bibliographic Details
Authors: Chatterjee, Arindom|||0000-0002-0861-2058, Chávez Ángel, Emigdio|||0000-0002-9783-0806, Ballesteros, Belén|||0000-0002-1958-8911, Caicedo Roque, Jose Manuel|||0000-0002-5192-4989, Padilla-Pantoja, Jessica|||0000-0002-7769-7753, Leborán, Víctor|||0000-0001-9806-3234, Sotomayor Torres, Clivia M.|||0000-0001-9986-2716, Rivadulla, Francisco|||0000-0003-3099-0159, Santiso, José|||0000-0003-4274-2101
Format: article
Publication Date:2020
Country:España
Institution:Universitat Autònoma de Barcelona
Repository:Dipòsit Digital de Documents de la UAB
Language:English
OAI Identifier:oai:ddd.uab.cat:235995
Online Access:https://ddd.uab.cat/record/235995
https://dx.doi.org/urn:doi:10.1039/d0ta04781c
Access Level:Open access
Keyword:Electrical conductivity
Epitaxial thin films
In-plane compressive strain
Preferred orientations
Single crystal substrates
Spontaneous generation
Temperature dependence
Thermoelectric properties
Description
Summary:This work describes the growth of thin epitaxial films of the layered perovskite material GdBaCoO(GBCO) on different single crystal substrates SrTiO(STO), (LaAlO)(SrTaAlO)(LSAT) and LaAlO(LAO) as an approach to study changes in the thermoelectric properties by means of the induced epitaxial strain. In addition to strain changes, the films grow with considerably different preferred orientations and domain microstructures: GBCO films on STO are purelyc-axis oriented (c) with an average 0.18% in-plane tensile strain; GBCO on LSAT is composed of domains with a mixed orientation (candc) with an average 0.71% in-plane compressive strain; while on LAO it isb-axis oriented (c) with an average 0.89% in-plane compressive strain. These differences result in important cell volume changes, as well as in the orthorhombicity of thea-bplane of the GBCO structure, which in turn induce a change in the sign and temperature dependence of the thermopower, while the electrical conductivity remains almost unchanged. In general, compressively strained films show negativeSthermopower (n-type) while tensile strained films show a positiveS(p-type) at low temperatures, probing the adaptive nature of the GdBaCoOcompound. These results point to the spontaneous generation of oxygen vacancies to partially accommodate the epitaxial stress as the main cause for this effect.

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